The present invention relates to a semiconductor device having a lead frame and, more particularly, to a semiconductor device having, as a characteristic feature, the shape of a nonconductive tape for bonding and fixing inner leads of a lead frame having the inner leads on the surface of the nonconductive tape.
In the lead frame of a conventional semiconductor device of this type, the distal end portions of inner leads are fixed by tapes consisting of a nonconductive resin to prevent the deformation of the inner leads.
FIG. 5 shows a part of an area corresponding to the inside of a package of a lead frame of the conventional semiconductor device. In FIG. 5, a semiconductor element 5 is mounted on an island 4 formed at the central portion of the lead frame, and the island 4 is supported by suspending leads 3. The distal ends of inner leads 1 formed toward the island 4 are connected to the electrodes of the semiconductor element 5 with metal thin lines (not shown). When the number of electrodes is increased, the number of inner leads corresponding to the electrodes is increased, and the distal ends of the inner leads 1 are micropatterned accordingly. For this reason, the inner leads 1 are easily deformed. Conventionally, four nonconductive insulating tapes 2 may be adhered to the inner leads 1 arranged at the four sides of the lead frame to prevent the deformation of the inner leads. In this case, each of the tapes has the shape of a rectangle, or as shown in FIG. 6C, corners of each of the rectangular tapes may partially cut to obtain tapes 2 each having C-shaped cut portions 2a.
Of the tapes of the above two types, the former, i.e., the rectangular tape, is used, when the tape is adhered to overlap the adjacent inner leads, the inner leads 1 are brought close to the suspending leads 3 due to the thermal shrinkage of the tape, short-circuiting disadvantageously occurs. For this reason, as shown in FIG. 6C, the tape is partially C-shaped cut to obtain the shape for preventing the short circuit.
Since each of the above conventional insulating tapes 2 has the shape shown in FIG. 6C, when the tapes 2 are cut out of a connected sheet-like tape base material 9 shown in FIG. 6A along cut lines 10 during the manufacture of the tapes, triangular pieces 2b must be cut off at C-shaped cut portions 2a.
The cut-off triangular tape pieces 2b, as shown in FIGS. 6A to 6C, are not easily and accurately discharged into a taping apparatus for cutting tapes, the tape pieces 2b are scattered near a lead frame apparatus, thereby disadvantageously decreasing the yield of semiconductor devices.
In order to prevent the above disadvantage, as shown in FIG. 7, tapes are punched out of a wide tape base material 19 along cut lines 11, a sheet-like remaining portion 2c from which the tapes are removed is left. In this case, however, the cost of materials for the tapes is increased by an increase in width of the tape base material.